Evidence that oxidative stress is higher in replacement gilts than in multiparous sows

The recent success obtained in term of increasing the litter size of sows has not correlated with a reduction of replacement rate. There is thus an increased economic demand for gilts with optimal reproductive potential and longevity. Unfortunately, replacement gilts are known to be more susceptible to diseases and less productive than multiparous sows. Interestingly, reproductive performance, resistance to diseases and longevity could all be largely affected by oxidative stress. To investigate whether oxidative stress conditions could account for the poor longevity of gilts, three distinct groups of conventional Yorkshire × Landrace sows were formed based on their similar age and parity (gilts, second parity sows as well as fourth to fifth parity sows). All animals were slaughtered during the post‐ovulatory period, and blood as well as tissue samples were collected. Biomarkers of oxidative damage to proteins (carbonyls) and DNA (8‐OHdG) were analysed in samples. Specific mRNA expression of major antioxidants such as glutathione peroxidases 1, 3 and 4 (GPx1, GPx3, GPx4) as well as superoxide dismutases 1 and 2 (Sod1, Sod2) were monitored in liver and kidney samples by quantitative RT‐PCR. Specific enzymatic activities of both GPx and SOD were measured by spectrophotometric assays. The plasma concentration of protein carbonyls was significantly different between the three groups with the highest concentration being observed in gilts (p ≤ 0.001). The mRNA expression levels of GPx1 and GPx4 were also significantly increased in the liver of gilts when compared to multiparous sows (p ≤ 0.05). SOD2 enzymatic activity was found to be higher in the liver of gilts than multiparous sows (p ≤ 0.05). Taken together, these results indicate that replacement gilts sustain significantly higher oxidative conditions than multiparous sows. Current findings may contribute to the design of nutritional regimens that will increase the productivity of gilts by counteracting oxidative stress.     

Estimates of Breed Average Direct,Maternal and Heterosis Effects for Some Pre-weaning Traits of Zebu Breeds and Their Crosses in Southeastern Mexico

Information on 936 birth weights (BW), adjusted weaning weights (AWW) and average daily gains (ADG) from Brahman (B), Indubrazil (I), Gyr (G) and commercial Zebu (C) cattle and their crosses were obtained from the records of a farm in the State of Yucatan, Mexico. Two statistical models were used to analyse the data: the first included the effects of year and season of birth, sex of the calf, cow's parity number and breed group. The other model included the same environmental effects as the previous model and the genetic components of breed group (breed additive, breed maternal and heterosis effects). Additive and maternal effects were expressed as deviations from those for the B breed. The means of BW, AWW and ADG for the B breed were 33.3 ± 0.64 kg, 204.0 ± 4.9 kg and 760.06 ± 19.24 g/day, respectively. Both models gave similar results in terms of the variance explained. Additive effects were significant (p < 0.05) for AWW and ADG but not for BW. The minor additive effect was for the C breed (−10.75 kg and −40.77 g for WW and ADG, respectively). Maternal and heterosis effects were not significant (p > 0.05) for any of the traits. The correlation between the breed group means and the means estimated by the prediction equation was r = 0.88. Finally, there was no significant genetic effect on pre-weaning calf performance among the genotypes evaluated. The genetic model can be used to predict the genotype means with a high degree of accuracy. This revised version was published online in July 2006 with corrections to the Cover Date.     

北疆奶牛隐性乳房炎的调查与分析

[目的]为了解北疆某牧场奶牛隐性乳房炎情况及分析其可能存在的风险因素。[方法]2020年1月至2022年9月通过加州乳房炎检测法（CMT）对该牧场在群泌乳牛进行隐性乳房炎调查,并初步分析该场可能存在的主要风险因素。[结果]该牧场2020—2022年各年奶牛隐性乳房炎平均阳性率分别为3.69%（110/2 980）、5.01%（150/2 993）和3.87%（86/2 220）;乳区阳性率分别为0.93%（110/11 856）、1.35%（160/11 880）和0.97%（86/8 860）;瞎乳头率分别为0.13%（16/11 920）、0.19%（23/11 972）和0.23%（20/8 880）;夏季隐性乳房炎阳性率明显高于其他季节,奶牛各乳区隐性乳房炎阳性率差异不显著（P>0.05）,不同胎次间的奶牛隐性乳房炎平均阳性率差异性显著（P<0.05）,5胎和6胎及以上牛的隐性乳房炎平均阳性率均明显高于其他胎次。[结论]该牧场奶牛隐性乳房炎发生率较低但仍需改善,夏季炎热潮湿的饲养环境和高龄奶牛更易发生热应激,奶牛身免疫力下降等原因可能是该牧场奶牛患乳房炎的主要风险因素。     

Effects of Parity of Dam and Breeding Date on the Litter Size of Inner Mongolia White Cashmere Goats

The article through the analysis and research to the effects of parity of dam and breeding date on the litter size of Inner Mongolia White cashmere goats,determine the optimal mating time of Inner Mongolia White cashmere goats,in order to improve the efficiency of reproductive.Data used were 1998 to 2013 reproductive performance records collected from the Arbas stock farm in Inner Mongolia,China.The GLM procedure of SAS 9.0 software was used to determine the significant effect of the parity of dam and breeding date,the results showed that the parity of dam and breeding date had significant effect on litter size (P< 0.01).Litter size was the lowest in 1st parity does (1.37),the significantly increase in litter size with advance in parity and decline after six parity;Mating cycles for September 29th to October 16th had the highest litter size (1.76),and the estrous months and estrus peak time mainly concentrated in October,so this stage in production could be used as breeding period of Inner Mongolia White cashmere goats.     

奶牛挤奶次数与泌乳期对鲜乳品质的影响

在奶牛泌乳期内分别采用每日2次或3次挤乳方式,以及在泌乳中期(100d)和泌乳后期(200d)由每日挤乳2次转换为3次。测定第1,第2和第3泌乳胎次以上奶牛的鲜乳产量及品质。结果表明,整个泌乳期采用每日3次挤乳方式,鲜乳产量增加10.4%,则鲜乳中蛋白质含量降低;在泌乳中期,鲜乳中酪蛋白占总蛋白的比例提高;而在泌乳前期和中期,鲜乳的酸度(ADV)提高。第2泌乳胎次以上的奶牛,在泌乳前期鲜乳的蛋白质含量和ADV值较高。第3泌乳胎次以上的奶牛,鲜乳中酪蛋白占总蛋白的比例较低,而胞浆素活性较高。在泌乳后期,即随着奶牛泌乳胎次的增加,鲜乳中酪蛋白占总蛋白的比例显著降低,而胞浆素活性随之增加。由于原料乳的起始ADV值较高,制备的液态乳制品在冷藏期间的ADV值继续增加,可能导致产品在货架期内较早地表现出腐败异味。     

大尾寒羊产羔数对胎次的回归分析

该研究利用SPSS软件分析了大尾寒羊产羔数对胎次的回归,大尾寒羊产羔数对胎次的二次方回归和三次方回归的拟合度(R2)分别为0.9246和0.9269,可见两种模型下的回归方程的拟合度都比较高。产羔数对胎次的二次方回归方程中的所有回归参数均达到极显著水平(P<0.01),说明大尾寒羊产羔数对胎次用二次方回归方程具有一定的应用价值。     

Factors Affecting Fertility According to the Postpartum Period in Crossbred Dual-Purpose Suckling Cows in the Tropics

To determine the relationship between first service conception rate (FSC) and the postpartum period (PP), 6160 calvings from 2250 crossbred dual-purpose cows were analysed. The effects of breed predominance (BT: Bos taurus and BI: Bos indicus), season of service (dry, intermediate and humid), parity (1 or 2 and more), agroecological region (Sub-humid and Dry Tropical Forest) and milk production were studied. The postpartum period was grouped according to the calving–first service interval as G1 ≤ 60 days (n = 1889); G2 > 60 ≤ 90 days (n = 1436); G3 > 90 ≤ 120 days (n = 1030); and G4 > 120 days (n = 1805). Data were analysed by chi-squared test. The overall mean for FSC was 58.2% and was lower in G1 (p < 0.01). All PP showed a breed effect on FSC, with mean values of 61.6% and 53.3% for BI and BT, respectively. Season of service also affected FSC, which was significantly lower during the humid period: 51.2% versus 57.4% and 61.5% for the intermediate and dry periods (p < 0.01), respectively. Parity and environmental effects were not observed on FSC. Levels of milk yield did influence the FSC, which decreased from 66.7% and 61.0% for milk yields of < 1500 kg and between 1501 and 2000 kg to 46.0% in milk yields > 2000 kg (p < 0.01).     

影响哺乳期羔羊生长的母羊因素分析

为探索母羊因素对哺乳期云上黑山羊羔羊生长发育的影响,根据母羊体重、胎次分别选取云上黑山羊初生羔羊90只和120只,公、母各半,从出生开始直至90日龄断奶,每10天进行1次体重测定,进行生长发育分析。结果表明:(1)母羊产后体重对羔羊初生重、哺乳期体重具有显著影响(P<0.05)。母羔中,38~45 kg母羊组和48~62 kg母羊组的羔羊初生重、平均日增重均显著高于28~35 kg母羊组(P<0.05)。公羔中,38~45 kg母羊组的羔羊初生重显著高于其他两组羔羊(P<0.05),48~62 kg母羊组其羔羊平均日增重显著高于其他两组羔羊(P<0.05)。(2)母羊胎次对母羔初生重没有显著影响,但对母羔哺乳期体重均有显著影响(P<0.05),母羔中,3胎、4胎母羊组的羔羊平均日增重均显著高于1胎和2胎母羊组;母羊胎次对公羔的影响不显著。说明母羊产后体重显著影响羔羊胎儿期和哺乳期的生长发育,合适的母羊体重可以为羔羊提供充足的营养;母羊胎次仅对哺乳期母羔具有显著影响,母羊的母性行为随胎次的增加而完善。     

Genetic parameters for litter traits at different parities in purebred Landrace and Yorkshire pigs

Comparison of the multi‐trait animal model and the traditional repeatability model was carried out using data obtained from 6,424 Landrace and 20,835 Yorkshire sows farrowed from January 2000 to April 2018 in order to estimate genetic parameters for litter traits at different parities. Specifically, records of the total number born (TNB), number born alive (NBA), total number of mortality (MORT), number of stillborn (NSB) and number of mummified pigs (MUM) were used. Although results showed the heterogeneity of heritability for litter traits at different parities, the mean heritability estimates from the multi‐trait model were found to be higher than those of the repeatability model for all traits in both pig breeds. In terms of genetic correlation between parities, a slight difference in genetic control in the first parity was noted for TNB and NBA in Landrace and Yorkshire pigs. The correlation between the first parity and later parities ranged from 0.48 to 0.74 for TNB and NBA in both breeds. Moreover, genetic correlation between parities for MORT and NSB was observed to be high for parities higher than 2 in Yorkshire pigs. For MUM, genetic correlation between the first and other parities was generally low in both breeds, indicating that culling pigs on the basis of MUM at the first parity could probably be unreasonable. Overall, the results of this study suggest that the multi‐trait approach for litter size traits is useful for the accurate estimation of genetic parameters.     

胎次、月份及背膘厚度对母猪繁殖性能的影响

为探明不同胎次、产仔月份及背膘厚度对母猪繁殖性能的影响,对福建省某猪场3 972窝长大二元母猪的繁殖记录进行统计,选择不同阶段长大二元母猪508头测定其背膘厚度并记录产仔情况,按胎次、产仔月份及背膘厚度分别对母猪繁殖性能的影响进行分析。结果表明：长大二元母猪3～6胎的产仔性能较好,第1胎总产仔数、初生均重较低,显著低于2～7胎（P<0.05）,产活仔数显著低于2～6胎（P<0.05）;总产仔数及产活仔数在2,3,5月份较高,在1,11,12月份较低,产死胎窝数母猪最多在7,8月份;配种背膘厚18～20 mm组的总产仔数、活仔数显著高于背膘厚度≥21 mm组（P<0.05）;断奶背膘厚16～20 mm组产仔性能较好但与其他组差异不显著（P>0.05）;产前背膘厚度为20～23 mm组的总产仔数、产活仔数显著高于10～15 mm组（P<0.05）,背膘厚度≥24 mm的母猪产死胎窝数比例最高为58%;泌乳阶段母猪背膘损失4～6 mm之间母猪断奶至下一次发情间隔时间最短,显著少于背膘损失>6 mm组及<0 mm组（P<0.05）。表明胎次、产仔月份、背膘厚度对母猪繁殖性能有较大影响。